Manufacture of nickel formate



1951 1. E. JOHNSON 2, 6,072

' MANUFACTURE OF NICKEL FORMATE Filed Sept. 13, 1950 FINELY DIVIDEDNICKEL METAL FORMIC ACID r REACTION MIXTURE CONTAINING METALLIC NICKEL.FORMIC ACID,WATER,

DISSOLVED NICKEL'FORMATE.

SOLID NICKEL FORMATE.

(CONTINUOUSLY AGITATED AT 90C. Io IOOC.)

WITHDRAW PORTION OF REACTION MIXTURE AND ALLOW TO SETTLE UNDER MILDAGITATION. ENOUGH TO KEEP THE SOLID NICKEL FORMATE IN SUSPENSION. REMOVENICKEL METAL.

FILTER OFF SOLID NICKEL FORMATE I Fl LTRAT E PRODUCT IRWIN E. JOHNSONINVENTOR.

Patented Nov. 20, 1951 UNITED STATES PATENT OFFICE MANUFACTURE OF NICKELFORMATE Irwin E. Johnson, Cleveland Heights, Ohio, as-

signor to The Harshaw Chemical Company, Elyria, Ohio, a corporation ofOhio Application September 13, 1950, Serial No. 184,565

4 Claims. 1

This invention relates to a method of producing nickel formate bydissolving nickel metal in formic acid.

Nickel fcrmate is used in large quantities in the catalytichydrogenation of oils, especially vegetable oils in the manufacture ofmargarine and vegetable shortenings. Nickel metal is the ultimatecatalyst, but the formate is reduced to metallic state in thehydrogenation reaction and may therefore be added, instead of reducednickel, to the charge of oil to be hydrogenated. Notwithstanding thelarge use of nickel formate for hydrogenation, the prevailin method ofpreparation has continued for perhaps thirty years to involveprecipitation of nickel carbonate from nickel sulfate solution by theuse of soda ash and reaction of the carbonate with formic acid. Nickelformate thus commercially prepared is contaminated with by-product saltsto an extent that it is seldom much, if any, above 99% purity.

While it is common practice to produce metal salts of strong acids bydirect attack of the acid on the metal in aqueous solution, it has notbeen supposed that such a corrosion-resistant metal as nickel could bedissolved in such a weak acid as formic acid at a rate such as would beadequate for production of the salt on a commercial basis. Mellor (vol.15, page 147) reproduces a diagram from Chemiker-Zeitung (Krulla, vol.54, pages 429-431, 1930) which indicates an exceedingly slow rate ofcorrosion of nickel by formic acid. Indeed Krulla indicates that aceticacid is several times more corrosive to nickel than formic acid. TheInternational Nickel Company, in a publication entitled Corrosion,published in 1944 gives the rate of corrosion of nickel by formic acidas four-thousandths of an inch per year. The same publication indicatescorrosion of metallic nickel by 90% formic acid to beeighteenthousandths of an inch per year at the temperature of boilingwater. Uhligs Corrosion Handbook (1948), page 260, indicates that aceticand formic acids are moderately corrosive to nickel as compared withother organic acids. Considerable quantitative information is given inregard to acetic acid indicating corrosion rates under varyingconditions varying from a few thousandths of an inch per year tothirty-four hundredths of an inch year year for 75% acid under thecombined effect of aeration and agitation. Formic acid should, accordingto the literature referred to, be less corrosive than acetic acid. Theabove literature references are concerned with corrosion and evidentlywere based upon studies wherein the investigator was chiefly interestedin avoiding the harmful effects of corrosion rather than any possibilityof manufacture of metal salts.

I have now discovered that it is feasible to produce nickel formate bythe action of formic acid on nickel metal under suitable conditions.

Attempts to produce nickel formate by adding powdered nickel metal toaqueous formic acid solutions at various temperatures on a beaker scaleindicated that a coating would be formed which would soon stop thereaction or slow it down to an unsatisfactory rate. At an elevatedtemperature, the reaction proceeded at a higher rate, but a hard cakewas soon formed in the bottom of the beaker. An attempt was made toovercome this situation by passing aqueuos formic acid solution througha reaction tube containing the nickel metal at such a rate that thesolution would not become saturated with respect to nickel formate, andthen separating the nickel formats from the resulting solution,returning the liquor with some addition of formic acid for furthercontact with the nickel metal. The amount of distillation necessary tocarry out this procedure proved excessive, the weight of nickel formaterecovered being only about 3% of the weight of liquor which had to beevaporated.

Inasmuch as the problem of the solid nickel formate coating on nickelmetal could not be avoided by keeping the formate in solution, at leastnot without excessive distillation cost, further investigation wasundertaken which led to the discovery that if the reaction temperatureis maintained in the region from C. to C., and agitation is continuous,the particles of nickel formate do not adhere to the particles of nickelmetal, and, because of the much higher specific gravity of the nickelmetal it is possible to separate it from the nickel formate.

Accordingly, I am able to produce nickel formate from nickel metal byestablishing a reaction mixture wherein formic acid in aqueuos solutionis brought into contact with nickel metal at a temperature in the rangefrom 90 C. to 110 C. with continuous agitation, withdrawing a portion ofthe reaction mixture which, on account of the agitation, contains allthe component thereof, separating from such withdrawn portion, byphysical means, the nickel metal, normally contaminated with nickelformate, and the nickel formate in condition substantially completelyfree of nickel metal, returnin the resulting parts of such withdrawnportion to the reaction mixture with the exception of the nickeliormate, and adding to the reaction. mixture formic acid, nickel metal,and water, sufficient to compensate for such amounts of these materialsas are removed as product or otherwise and not returned as aboveindicated. The physical means of separation referred to may be asettling procedure wherein the liquor is agitated sufiiciently tosuspend the nickel formate, but not sumciently to suspend the particlesof nickel metal. Under such conditions the nickel metal will concentrateat the bottom together with some adherent nickel formate while thenickel formate will be dis.- tributed through the liquid, permittin thelatter to be drawn off and filtered for the recovery of nickel formate-After the nickel formate slurry has been drawn off, it may be allowed tosettle and the liquor decanted off instead of filtering. Again, theseparation of the components of the withdrawn portion of the reactionmixture may be accomplished by the use of a centrifugeof con.- tinuousor other type whereby greater speed can be achieved than with thesimpler sedimentation method. It is of greatest importance that there beno long-continued interruptions in the'agitation of the reactionmixture. Some interruption can be tolerated and, with short intervals,inter-. mittent agitation can be employed. Agitation which ischaracterized by interruptions of only such short duration that nosubstantialagglomeration take place is to be considered. as com,-prehended within the term continuous.

The accompanying drawing is a flow-sheet diagram illustrating thepresent preferred embodiment of the invention. 1

The nickel metal employed should be finely? divided, but it is notessential that all the particles be in the same state of subdivision. A

commercial product known as steam shattered shot can be very successfulyused. This material is a mixture of particle sizes varying from perhapsof an inch in diameter to powder or dust. lhe major portion would passthrough a 30 mesh screen, and a substantial portion through a 100 meshscreen. Very little, perhaps lessthan 10%, would remain on a 4 meshscreen. It is, not essential that a material'of such fine state ofsubdivision as steam shattered shot should be used; however, in order tosecure a satisfactory rate of nickel formate production, the majorportion of the particles of metal should pass a 30 mesh screen, and atleast 90% shouldpass a 4 mesh screen.

The efiect of agitation is related not only to prevention of cementationof the particles of nickel formate on the particles of nickel metal andthe consequent formation of agglomerates, but also to the rate ofreaction, therelative movement between the solution and the metallicsurface being essential to keep the metal particles clean of reactionproduct which would slow down the reaction aswell as causing cementationof the particles into agglomerates. It is not essential that theagitation be extremely vigorous, so long as it-is continuous, and suchagitation as is produced'by boiling the reaction mixture may besatisfactory. Even a lesser degree of agitation may be adequate but agentle boiling of the reaction mixture accompanied by mechanicalstirring is preferable.

The range of concentration of formic acid which can be employed israther wide. A'reasenable rate of reaction can be had with solutions asdilute as 30% by weight and up to 100%. but the preferred concentrationrange is from 60% to 85%, based on the combined weight of formic acidand water present in the reaction mixture.

By establishing a reaction mixture from which material is continuouslyremoved, or is removed in successive portions, and returning to suchreaction mixture all the content of the removed material except thenickel formate, there results the possibility of merely adding from timeto time, or continuously, a replenishing amount of nickel metal and offormic acid, so that any relatively large particles of nickel willsimply, in effect, remain in the reaction mixture until consumed. Suchlarge particles will naturally require a longer time for-completeconsumption, but if the proportion is not too large, the process may beoperated at a satisfactory rate without undue build-up of relativelylarge particles of metal. As above indicated, the particle size of themetal is not sharply critical and, with large enough equipment andadequate agitation, any size pieces of nickel can be used, but particlesize is related to the rate of reaction, so that, for practicalpurposes, the nickel should be finely divided.

By reference to the drawing, it will beseen that formic acid solution iscaused to react with metallic nickel to an extent that the liquidportion of the reaction mixture will not dissolve all of the nickelformate, and solid nickel. formats precipitates in the reaction mixture.Under the essential conditions as above indicated, the re action will gobeyond saturation of the solution with nickel formats, nickel formatebeing formed at the surface of the metal, taken into solution, andprecipitated out again from solution whereby the solid portion of thereaction mixture becomes a mixture of solid nickel formate and solidnickel metal. Continuous agitation prevents the solution andprecipitation from taking place atone V and the same point as wouldhappen under conditions of no agitation. When the proportion of solidnickel formate has built up in the reactign mixture to a practicalextent, I then remove a portion of the reaction mixture eithercontinuously or in successive removals, and separate the nickel formatetherefrom in the manner above.in-. dicated. The portion of the reactionmixture sl bjected to separation can be the entire amount,v

but I'consider it more practical to remove it continuously, andcontinuously subject there,-

moved portion to separation as indicated; 1 find Accordingly, I preferto withdraw slurry continue ously-from a homogeneous reaction mixtureand separate the nickel metal from the slurry so withdrawn by physicalmeans based upon its higher specific gravity (or possibly upon itsmagnetic properties) and return it to the reaction mixture. 1' thenseparate the solid nickel formats from the l quid b fi trat n dimenta oo t ke and return the liquid to the reaction mixture, all as indicatedin the drawing. Continuous operation of the various steps in the processis desirable,

however intermittent operation of some or allis. possible and is to beconsidered theequivalent of tly continuou era i n and com reh nded intheword continuous.

The following specific example will serve to illustrate the invention:

Example I Into a suitable reaction vessel were introduced 120 parts byweight of nickel in the form of steam shattered shot, and 200 parts byweight of 85% formic acid. The temperature was brought up to the boilingpoint of the mixture, and boiling was continued for a period of fourhours, the mixture being vigorously agitated by a propeller-typestirring device. At the end of four hours the agitator was stopped. Thenickel was allowed to settle under slight agitation, and the suspensionof nickel formate was decanted off and filtered.

It will be seen that by returning the filtrate to the reaction vesseltogether with additional portions of nickel metal and formic acid, the

conditions are suitable for the succeeding batch. g

The amount of nickel metal dissolved was 10.5 parts by weight, amountingto 8.75% of the batch. The product showed on analysis 99.9 per cent ofnickel formate dihydrate.

Having thus described my invention, what I claim is:

1. A process for producing nickel formate comprising establishing areaction mixture wherein finely-divided nickel metal is brought into contact with formic acid at a temperature within a range from 90 C. to 1100., continuing the reaction, with continuous agitation, until asubstantial proportion of the nickel has reacted with the formic acid toproduce a substantial quantity of nickel formate over and above theamount required to saturate the reaction mixture, whereby the reactionmixture contains a substantial proportion of solid nickel formate,subjecting at least a portion of the resulting reaction mixture tomechanical separation for removal therefrom of the unreacted nickelmetal and separating solid nickel formate from the resulting slurry.

2. A process for producing nickel formate comprising establishing areaction mixture wherein finely-divided nickel metal is brought intocontact with formic acid in aqueous solution at a temperature within arange from 90 C. to 110 C., continuing the reaction with continuousagitation until a substantial proportion of the nickel has reacted withthe formic acid to produce a substantial quantity of nickel formate overand above the amount required to saturate the reaction mixture, wherebythe reaction mixture contains a substantial proportion of solid nickelformate, subjecting at least a portion of the resulting reaction mixtureto mechanical separation for removal therefrom of the unreacted nickelmetal, separating the solid nickel formate from the resulting slurry andreturning to the reaction mixture the liquid and metallic nickel contentof said separated portion.

3. In a continuous process for producing nickel formate, establishing areaction mixture in a reaction vessel, said reaction mixture beingcomposed of water, formic acid, nickel metal, and nickel formate, theliquid portion of said mixture being saturated with respect to nickelformate, continuously agitating said mixture, continuously withdrawingfrom said reaction vessel a slurry containing each of said components ofthe reaction mixture, separating from said slurry a fraction principallycomposed of metallic nickel and returning it to the reaction vessel, andthen separating from the remainder of said slurry a fraction principallycomposed of solid nickel formate substantially free of metallic nickel,and returning the liquid portion of said slurry and replenishing amountof nickel metal and formic acid to said reaction vessel.

4. In a continuous process for producing nickel formate, establishing areaction mixture in a reaction vessel, said reaction mixture beingcomposed of water, formic acid, nickel metal in a state of subdivisionto pass 90% through a 4- mesh screen and more than 50% through a 30-mesh screen, and nickel formate, the liquid portion of said mixturebeing saturated with respect to nickel formate, continuously agitatingsaid mixture, maintaining the temperature of the reaction mixture atfrom 90 C. to 110 C., the concentration of formic acid being from to ofthe combined weight of water and formic acid, continuously withdrawingfrom said reaction vessel a slurry containing each of said components ofthe reaction mixture, continuously separating from said slurry afraction principally composed of metallic nickel and returning it to thereaction vessel, and continuously separating from the remainder of saidslurry a fraction principally composed of solid nickel formatesubstantially free of metallic nickel, and continuously returning theliquid portion of said slurry and replenishing amounts of nickel metaland formic acid to said reaction vessel.

IRWIN E. JOHNSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,452,478 Ellis Apr. 17, 19232,431,997 .011 Rose Dec. 2, 194;7

1. A PROCESS FOR PRODUCING NICKEL FORMATE COMPRISING ESTABLISHING AREACTION MIXTURE WHEREIN FINELY-DIVIDED NICKEL METAL IS BROUGH INTOCONTACT WITH FORMIC ACID AT A TEMPERATURE WITHIN A RANGE FROM 90* C. TO110* C., CONTINUING THE REACTION, WITH CONTINUOUS AGITATION, UNTIL ASUBSTANTIAL PROPORTION OF THE NICKEL HAS REACTED WITH THE FORMIC ACID TOPRODUCE A SUBSTANTIAL QUANTITY OF NICKEL FORMATE OVER AND ABOVE THEAMOUNT REQUIRED TO SATURATE THE REACTION MIXTURE, WHEREBY THE REACTIONMIXTURE CONTAINS A SUBSTANTIAL PROPORTION OF SOLID NICKEL FORMATE,SUBJECTING AT LEAST A PORTION OF THE RESULTING REACTION MIXTURE TOMECHANICAL SEPARATION FOR REMOVAL THEREFROM OF THE UNREACTED NICKELMETAL AND SEPARATING SOLID NICKEL FORMATE FROM THE RESULTING SLURRY.